Battery tester for electric vehicle

ABSTRACT

Testing or diagnostics are performed on an electric vehicle. The vehicle is operated and current flow through a system of the vehicle is monitored. A voltage related to the system is also monitored. Diagnostics are provided based upon the monitored voltage and the monitored current.

CROSS-REFERENCE TO RELATED APPLICATION

The present application is a Continuation-In-Part of Ser. No.12/174,894, filed Jul. 17, 2008, which is based on and claims thebenefit of U.S. provisional patent application Ser. No. 60/950,182,filed Jul. 17, 2007, and U.S. provisional patent application Ser. No.60/970,319, filed Sep. 6, 2007, the contents of which are herebyincorporated by reference in their entirety.

BACKGROUND OF THE INVENTION

The present invention relates to test equipment for electric vehicles.More specifically, the present invention relates to a tester for testingelectrical systems of an electric vehicle.

Various types of electronic battery tester are known in the art.Electronic battery techniques have been pioneered by Midtronics, Inc. ofWillowbrook, Ill. and Dr. Keith S. Champlin. Examples are shown anddescribed in U.S. Pat. No. 3,873,911, issued Mar. 25, 1975, to Champlin;U.S. Pat. No. 3,909,708, issued Sep. 30, 1975, to Champlin; U.S. Pat.No. 4,816,768, issued Mar. 28, 1989, to Champlin; U.S. Pat. No.4,825,170, issued Apr. 25, 1989, to Champlin; U.S. Pat. No. 4,881,038,issued Nov. 14, 1989, to Champlin; U.S. Pat. No. 4,912,416, issued Mar.27, 1990, to Champlin; U.S. Pat. No. 5,140,269, issued Aug. 18, 1992, toChamplin; U.S. Pat. No. 5,343,380, issued Aug. 30, 1994; U.S. Pat. No.5,572,136, issued Nov. 5, 1996; U.S. Pat. No. 5,574,355, issued Nov. 12,1996; U.S. Pat. No. 5,583,416, issued Dec. 10, 1996; U.S. Pat. No.5,585,728, issued Dec. 17, 1996; U.S. Pat. No. 5,589,757, issued Dec.31, 1996; U.S. Pat. No. 5,592,093, issued Jan. 7, 1997; U.S. Pat. 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No. 09/780,146, filed Feb. 9,2001, entitled STORAGE BATTERY WITH INTEGRAL BATTERY TESTER; U.S. Ser.No. 09/756,638, filed Jan. 8, 2001, entitled METHOD AND APPARATUS FORDETERMINING BATTERY PROPERTIES FROM COMPLEX IMPEDANCE/ADMITTANCE; U.S.Ser. No. 09/862,783, filed May 21, 2001, entitled METHOD AND APPARATUSFOR TESTING CELLS AND BATTERIES EMBEDDED IN SERIES/PARALLEL SYSTEMS;U.S. Ser. No. 09/880,473, filed Jun. 13, 2001; entitled BATTERY TESTMODULE; U.S. Ser. No. 10/042,451, filed Jan. 8, 2002, entitled BATTERYCHARGE CONTROL DEVICE; U.S. Ser. No. 10/109,734, filed Mar. 28, 2002,entitled APPARATUS AND METHOD FOR COUNTERACTING SELF DISCHARGE IN ASTORAGE BATTERY; U.S. Ser. No. 10/112,998, filed Mar. 29, 2002, entitledBATTERY TESTER WITH BATTERY REPLACEMENT OUTPUT; U.S. Ser. No.10/263,473, filed Oct. 2, 2002, entitled ELECTRONIC BATTERY TESTER WITHRELATIVE TEST OUTPUT; U.S. Ser. No. 10/310,385, filed Dec. 5, 2002,entitled BATTERY TEST MODULE; U.S. Ser. No. 10/653,342, filed Sep. 2,2003, entitled ELECTRONIC BATTERY TESTER CONFIGURED TO PREDICT A LOADTEST RESULT; U.S. Ser. No. 09/653,963, filed Sep. 1, 2000, entitledSYSTEM AND METHOD FOR CONTROLLING POWER GENERATION AND STORAGE; U.S.Ser. No. 10/174,110, filed Jun. 18, 2002, entitled DAYTIME RUNNING LIGHTCONTROL USING AN INTELLIGENT POWER MANAGEMENT SYSTEM; U.S. Ser. No.10/258,441, filed Apr. 9, 2003, entitled CURRENT MEASURING CIRCUITSUITED FOR BATTERIES; U.S. Ser. No. 10/681,666, filed Oct. 8, 2003,entitled ELECTRONIC BATTERY TESTER WITH PROBE LIGHT; U.S. Ser. No.10/791,141, filed Mar. 2, 2004, entitled METHOD AND APPARATUS FORAUDITING A BATTERY TEST; U.S. Ser. No. 10/867,385, filed Jun. 14, 2004,entitled ENERGY MANAGEMENT SYSTEM FOR AUTOMOTIVE VEHICLE; U.S. Ser. No.10/958,812, filed Oct. 5, 2004, entitled SCAN TOOL FOR ELECTRONICBATTERY TESTER; U.S. Ser. No. 60/587,232, filed Dec. 14, 2004, entitledCELLTRON ULTRA, U.S. Ser. No. 11/018,785, filed Dec. 21, 2004, entitledWIRELESS BATTERY MONITOR; U.S. Ser. No. 60/653,537, filed Feb. 16, 2005,entitled CUSTOMER MANAGED WARRANTY CODE; U.S. Ser. No. 60/665,070, filedMar. 24, 2005, entitled OHMMETER PROTECTION CIRCUIT; U.S. Ser. No.60,694,199, filed Jun. 27, 2005, entitled GEL BATTERY CONDUCTANCECOMPENSATION; U.S. Ser. No. 11/178,550, filed Jul. 11, 2005, entitledWIRELESS BATTERY TESTER/CHARGER; U.S. Ser. No. 60/705,389, filed Aug. 4,2005, entitled PORTABLE TOOL THEFT PREVENTION SYSTEM, U.S. Ser. No.11/207,419, filed Aug. 19, 2005, entitled SYSTEM FOR AUTOMATICALLYGATHERING BATTERY INFORMATION FOR USE DURING BATTERY TESTER/CHARGING,U.S. Ser. No. 60/712,322, filed Aug. 29, 2005, entitled AUTOMOTIVEVEHICLE ELECTRICAL SYSTEM DIAGNOSTIC DEVICE, U.S. Ser. No. 60/713,168,filed Aug. 31, 2005, entitled LOAD TESTER SIMULATION WITH DISCHARGECOMPENSATION, U.S. Ser. No. 60/731,881, filed Oct. 31, 2005, entitledPLUG-IN FEATURES FOR BATTERY TESTERS; U.S. Ser. No. 60/731,887, filedOct. 31, 2005, entitled AUTOMOTIVE VEHICLE ELECTRICAL SYSTEM DIAGNOSTICDEVICE; U.S. Ser. No. 11/304,004, filed Dec. 14, 2005, entitled BATTERYTESTER THAT CALCULATES ITS OWN REFERENCE VALUES; U.S. Ser. No.60/751,853, filed Dec. 20, 2005, entitled BATTERY MONITORING SYSTEM;U.S. Ser. No. 11/304,004, filed Dec. 14, 2005, entitled BATTERY TESTERWITH CALCULATES ITS OWN REFERENCE VALUES; U.S. Ser. No. 60/751,853,filed Dec. 20, 2005, entitled BATTERY MONITORING SYSTEM; U.S. Ser. No.11/356,443, filed Feb. 16, 2006, entitled ELECTRONIC BATTERY TESTER WITHNETWORK COMMUNICATION; U.S. Ser. No. 11/498,703, filed Aug. 3, 2006,entitled THEFT PREVENTION DEVICE FOR AUTOMOTIVE VEHICLE SERVICE CENTERS;U.S. Ser. No. 11/511,872, filed Aug. 29, 2006, entitled AUTOMOTIVEVEHICLE ELECTRICAL SYSTEM DIAGNOSTIC DEVICE; U.S. Ser. No. 11/519,481,filed Sep. 12, 2006, entitled BROAD-BAND LOW-CONDUCTANCE CABLES FORMAKING KELVIN CONNECTIONS TO ELECTROCHEMICAL CELLS AND BATTERIES; U.S.Ser. No. 60/847,064, filed Sep. 25, 2006, entitled STATIONARY BATTERYMONITORING ALGORITHMS; U.S. Ser. No. 11/641,594, filed Dec. 19, 2006,entitled METHOD AND APPARATUS FOR MEASURING A PARAMETER OF A VEHICLEELECTRONIC SYSTEM; U.S. Ser. No. 11/711,356, filed Feb. 27, 2007,entitled BATTERY TESTER WITH PROMOTION FEATURE; U.S. Ser. No.11/811,528, filed Jun. 11, 2007, entitled ALTERNATOR TESTER; U.S. Ser.No. 60/950,182, filed Jul. 17, 2007, entitled BATTERY TESTER FOR HYBRIDVEHICLE; U.S. Ser. No. 60/973,879, filed Sep. 20, 2007, entitledELECTRONIC BATTERY TESTER FOR TESTING STATIONARY BATTERIES; U.S. Ser.No. 11/931,907, filed Oct. 31, 2007, entitled BATTERY MAINTENANCE WITHPROBE LIGHT; U.S. Ser. No. 60/992,798, filed Dec. 6, 2007, entitledSTORAGE BATTERY AND BATTERY TESTER; U.S. Ser. No. 12/099,826, filed Apr.9, 2008, entitled BATTERY RUN DOWN INDICATOR; U.S. Ser. No. 61/061,848,filed Jun. 16, 2008, entitled KELVIN CLAMP FOR ELECTRONICALLY COUPLINGTO A BATTERY CONTACT; U.S. Ser. No. 12/168,264, filed Jul. 7, 2008,entitled BATTERY TESTERS WITH SECONDARY FUNCTIONALITY; U.S. Ser. No.12/174,894, filed Jul. 17, 2008, entitled BATTERY TESTER FOR ELECTRICVEHICLE; U.S. Ser. No. 12/204,141, filed Sep. 4, 2008, entitledELECTRONIC BATTERY TESTER OR CHARGER WITH DATABUS CONNECTION; U.S. Ser.No. 12/328,022, filed Dec. 4, 2008, entitled STORAGE BATTERY AND BATTERYTESTER; U.S. Ser. No. 12/416,457, filed Apr. 1, 2009, entitled SYSTEMFOR AUTOMATICALLY GATHERING BATTERY INFORMATION; U.S. Ser. No.12/416,453, filed Apr. 1, 2009, entitled INTEGRATED TAG READER ANDENVIRONMENT SENSOR; U.S. Ser. No. 12/416,445, filed Apr. 1, 2009,entitled SIMPLIFICATION OF INVENTORY MANAGEMENT; U.S. Ser. No.12/485,459, filed Jun. 16, 2009, entitled CLAMP FOR ELECTRONICALLYCOUPLING TO A BATTERY CONTACT; U.S. Ser. No. 12/498,642, filed Jul. 7,2009, entitled ELECTRONIC BATTERY TESTER; U.S. Ser. No. 12/697,485,filed Feb. 1, 2010, entitled ELECTRONIC BATTERY TESTER; U.S. Ser. No.12/698,375, filed Feb. 2, 2010, entitled ELECTRONIC BATTERY TESTER; U.S.Ser. No. 12/712,456, filed Feb. 25, 2010, entitled METHOD AND APPARATUSFOR DETECTING CELL DETERIORATION IN AN ELECTROCHEMICAL CELL OR BATTERY;U.S. Ser. No. 61/311,485, filed Mar. 8, 2010, entitled BATTERY TESTERWITH DATABUS FOR COMMUNICATING WITH VEHICLE ELECTRICAL SYSTEM U.S. Ser.No. 61/313,893, filed Mar. 15, 2010, entitled USE OF BATTERYMANUFACTURE/SELL DATE IN DIAGNOSIS AND RECOVERY OF DISCHARGED BATTERIES;which are incorporated herein in their entirety.

Many electric vehicles use a storage battery pack or other electricalstorage device, to store energy for use in operating the electricvehicle. Some such electric vehicles use energy recovery (or“regeneration”) techniques in which potentially waste energy isrecovered and stored in the energy storage device. One example isrecovery of energy from braking function. The energy in braking isrecovered as electrical energy rather than being dissipated as excessheat. Preferably, the energy storage device is able to efficiently storethe excess energy, as well as deliver energy to an electrical motor ofthe electric vehicle. Due to the increasing price of petroleum, hybridsystems are rapidly proliferating. There is an ongoing need to test theelectrical systems of such electric vehicles.

SUMMARY OF THE INVENTION

Testing or diagnostics are performed on an electric vehicle. The vehicleis operated and current flow through a system of the vehicle ismonitored. A voltage related to the system is also monitored.Diagnostics are provided based upon the monitored voltage and themonitored current.

BRIEF DESCRIPTION OF THE DRAWINGS

FIG. 1 is a simplified block diagram showing a battery tester inaccordance with the present invention coupled to a electric vehicle.

FIG. 2 is a simplified block diagram showing steps in accordance withthe present invention.

FIG. 3 is a simplified block diagram which illustrates a test device inaccordance with the present invention.

FIG. 4 is a simplified block diagram showing one aspect of the presentinvention in which the test device couples to the databus of theelectric vehicle.

DETAILED DESCRIPTION OF ILLUSTRATIVE EMBODIMENTS

Electric vehicles and hybrid vehicles are becoming increasingly popularas an alternative to traditional vehicles which are powered solely by aninternal combustion engine. In a electric vehicle, a large battery or agroup of batteries, or other energy storage device, is used to storeelectrical energy. The stored electrical power is used by an electricmotor to power the electric vehicle.

In order to increase energy efficiency, some electric vehicles usevarious techniques to capture or otherwise recover waste energy. Thismay be referred to as “regeneration”. The recovered energy is typicallyreturned in the battery of the electric vehicle for storage andsubsequent use.

Various techniques are used to recover energy. For example, one commontechnique is to use the braking system of the electric vehicle toconvert vehicle motion into electricity for storage in the battery. Thisdiffers from a conventional braking system in which excess energy isvented into the atmosphere as heat.

As the battery of the electric vehicle ages, its ability to store energyalso degrades. However, this may not be apparent to the operator,particularly in a hybrid vehicle. One symptom of a failing battery isdecreased mileage of the electric vehicle because the battery is notable to effectively store or deliver energy. The health of a battery ina electric vehicle is an indication of how well the battery accepts acharge and is able to deliver stored energy at high discharge rates. Tosome extent, this relates to the amp hour capacity of the battery aswell as the ability of the battery to accept or deliver charge in agiven time. This is related to how much recovered energy can be storedat one time for use at a later time. For example, is the battery capableof storing energy from many braking cycles for subsequent use, or is itonly able to store energy from a few such braking cycles.

Typical battery testing techniques are difficult to implement in such aelectric vehicle. For example, it may be difficult or impossible toaccess the individual batteries of a battery pack for testing. Suchaccess may require a great deal of labor. Further, there may be safetyconcerns related to the relatively high voltages involved if the batterypack is disassembled for testing.

With the present invention, a current sensor is coupled to the batterypack of a electric vehicle of the type which includes an electric motorto move the electric vehicle. The current sensor can be placed in linewith the battery pack and arranged to measure current into and out ofthe pack. The total string voltage of the battery pack is also measured.A technician or other service personnel performs a battery test byoperating the electric vehicle through a number of braking andacceleration cycles. Data is collected and compared to baseline ornominal data which is representative of operation of a new electricvehicle. An output can be provided based upon the comparison. Forexample, the output can be an indication of how well the electricvehicle compares to new electric vehicle, for example as a percentage.

The current sensor can be placed in series with one of the batteryterminals using a shunt resistance or the like. Another example is aHall effect or other non-intrusive sensor. Such a sensor is advantageousbecause it does not require the battery to be disconnected. In anotherexample, an adapter can be configured which can be inserted between thebattery pack and the electric vehicle such that the test device can becoupled to the battery.

The various sensors can be coupled at any convenient location, forexample, proximate the battery pack, under the hood, near the electricvehicle motor or other electronics. In such an application, a Halleffect sensor may be sufficient because of the relatively largemagnitudes of the current levels being monitored. Further, a Hall effectsensor may be easily “zeroed” because during installation there will beno current flowing. Voltage measurements may be made using directattachment, for example, to the high voltage pole of the battery. Thevoltage and current measurements may also be obtained through othertechniques, for example, through an OBDII interface used to readelectrical parameters from the electric vehicle computer system.

During testing, the test device can provide instructions to an operatoras to how to operate the electric vehicle. Such instructions can beprovided, for example, through a wireless communication link to a deviceproximate the operator, through a PDA-type device, through audibleinstructions, through a display of the vehicle, or through othertechniques.

If the testing device couples to the OBDII system of the electricvehicle, additional information can be retrieved. For example,information related to the speed (RPM) of a motor, speed of the electricvehicle, braking information, etc. can be recovered. With thisadditional information, the test device may be used to verify that thetechnician has performed the required operations. Such operations shouldhave some flexibility in order to reflect safe driving conditions.

FIG. 1 is a simplified block diagram 10 of a electric vehicle 12 coupledto a test device 14. The test device is shown as locate separate fromthe electric vehicle 12 and may be a portable or stationary device.However, in some configurations the test device 14 may be included inelectric vehicle 12. Electric vehicle 12 is illustrated as includingbattery pack 20, electric motor 22 and energy recovery device 24. Asdiscussed, the battery pack 20 is used to power the electric motor 22while the energy recover device 24 is used to recover energy duringelectric vehicle operation. Test circuitry 14 couples to battery 20 andincludes or is coupled to voltage sensor 30, memory 32 andmicroprocessor 33. Further, test circuitry 14 includes or is coupled toa current sensor 34 arranged to sensor current into and/or out ofbattery pack 20. Test circuitry 14 provides an output throughinput/output (I/O) 35 as discussed above related to the condition of thebattery pack 20. The test circuitry 14 includes a microprocessor 33 orthe like which may include either internal or external analog to digitalconverters configured to convert the sensed voltage current levels todigital values. Microprocessor 33 operates in accordance withinstructions stored in memory and provide an output 35 which is relatedto the condition of the battery pack 20. FIG. 1 also shows an optionalinternal combustion engine 40 which is used to supplement the energydelivered by battery pack 20. The optional engine 40 can be used tocharge battery pack 20, and/or can be used to supplement the electricalpower available to motor 22 during times of high acceleration or thelike. Thus, engine 40 may include an electric generator 41. Similarly,engine 40 can be configured to provide power directly to wheels or othercomponents of the vehicle 12. The connection of test device 14 to thevehicle 12 may be through an electrical connection to sensors such asthe voltage sensor 30 and the current sensor 34. Additionally, thevoltage sensor 30 and current sensor 34 can comprise components withinthe vehicle 12. In such a configuration, test device 14 can couple tothe vehicle through a data connection to the vehicle, for example, anOBDII connection to the vehicle in which current and voltage informationare read back from the vehicle. For example, the data can be recoveredas it is transmitted on the vehicle databus or the data can be retrievedby placing commands on the databus to access the desired information.

FIG. 2 is a simplified block diagram showing steps in accordance withone example embodiment of the present invention. The block diagram ofFIG. 2 begins at start block 50 and controls past block 52 where theelectric vehicle is operated and data is collected. At block 54, nominaldata is recovered. For example, such nominal data can be stored inmemory 32 shown in FIG. 1. The nominal data can be related to a baselinecondition, for example, the condition of the battery pack and/or inelectric vehicle 12 when they are new. At block 56, the collected datais compared to the nominal data and an output is provided at block 58.The output can be, for example, a relative output with respect to thecurrent condition of electric vehicle in battery relative to a newelectric vehicle or battery. This may be in the form of, for example, apercentage or other format. At block 60, the process is terminated.

FIG. 3 is a simplified block diagram showing test device 14 in greaterdetail. Test device 14 is illustrated as including differentialamplifier 102 which couples to current sensor 34. A second differentialamplifier 98 couples to battery 20 and forms the voltage sensor 30. Thevoltage sensor 30 may be a part of, or may be separated from, the testdevice 14. The output from the amplifier 98 is provided to an analog todigital converter 100 which couples microprocessor 33. Similarly, theoutput of amplifier 102 is converted into a digital format formicroprocessor 33 using analog to digital converter 104. The actualvoltage and current sensors may be in accordance with any technique andare not limited to the techniques described herein. As discussed below,the current and voltage sensors may be a part of vehicle 12 and the testcan retrieve their information over a databus of the vehicle.

Microprocessor 33 operates in accordance with instructions stored inmemory 32 and is configured to communicate with an operator through userinput/output (I/O) 110. An optional OBDII interface, as illustrated atOBDII I/O 112, is provided. OBDII I/O 112 is configured to couple to theOBDII databus of the electric vehicle 12. The user I/O 110 can be anytype of user input and output including, for example, a button or keypadentry, a display including a graphical display, an audio outputincluding voice prompts, or other input or output techniques.

FIG. 4 is a simplified block diagram showing another aspect of thepresent invention. As discussed above, test device 14 couples to the onboard databus 130 of electric vehicle 12, for example through OBDIIconnector 132. Electric vehicle 12 is illustrated as including aplurality of systems identified as System A, B, C through System N.These systems can be any active or passive electrical component or setof components within the vehicle including a motor or motors of thevehicle, an energy recovery system such as a regenerative brakingsystem, a battery cell, a block of cells, a battery pack, vehicleelectronics such as audio systems, defrosters, wipers, adjustable seatmotors, seat heaters, internal and external lights, computer systems,electrical systems associated with an electric or internal combustionmotor, charging systems, or others. Each of the systems A-N isillustrated as having a current sensor 140A-140N, respectively and avoltage sensor 142A-142N, respectively. The multiple current sensors 140and voltage sensors 142 are provided for illustrative purposes only anda particular system within the vehicle may be have neither type ofsensor, may have a single sensor, or may have multiple sensors. Theoutputs from the current sensors 140 the voltage sensors 142 areprovided to the internal databus of the electric vehicle 130. Theelectric vehicle 12 may include additional sensors for sensing physicalproperties such as temperature, moisture content, fluid levels,pressures, speed or rate of rotation of motors, flow rate, whether aswitch is opened or closed, etc. These sensors are illustrated in FIG. 4as sensor A, B through sensor N and are also coupled to the databus 130of electric vehicle 12. The sensors A, B, . . . N may be associated withany of the above discussed systems A-N, or with other components oraspects of the electric vehicle 12. For example, a particular sensor mayprovide a temperature reading of a particular system, or othermeasurement related to the system. Note that the coupling of the varioussensors to the databus 130 may be direct or indirect. For example, datafrom a particular sensor may be provided to another component, such asdirectly to a microprocessor 150 of the electric vehicle. Subsequently,the microprocessor 150 may provide the information on databus 130. Thedata from the various sensors may be optionally stored in an internalmemory 152 of the electric vehicle 12. In FIG. 4, the memory 152 isillustrated as being coupled to microprocessor 150. However, this may beoptional and the memory 152 can be coupled to databus 130, eitherdirectly or through some other component. In one aspect of the presentinvention, test device 14 monitors information from sensors within theelectric vehicle in order to provide enhanced diagnostics withoutrequiring connection of additional sensors to the electric vehicle 12.This is achieved by retrieving data through the databus 130 of theelectric vehicle as the various sensors within the vehicle communicateinformation.

In measuring electrical parameters of components, it is often desirableto couple to the electrical component through a four point “Kelvin”connection. In such a configuration, a first pair of connections areused to measure a voltage across the component while a second pair ofconnections are used to carry current. Kelvin connections reduce errorsin the measurements associated with the electrical leads and wiringwhich are used to couple to the component. However, in many electricvehicles, it is extremely difficult to place Kelvin connectors onto thevarious electrical components. Further, even if such connections aremade, they may carry high voltages which may be unsafe for an operator.Therefore, it is often difficult to couple to the electrical systems ofan electric vehicle using traditional Kelvin connection techniques whichhave been associated with the automotive industry.

In one aspect, the present invention provides a “virtual Kelvin”connection to electrical components of the vehicle. The “virtual Kelvin”connection is embodied in microprocessor 33 of the test device 14.Microprocessor 33 receives current and voltage information from a pairof sensors, such as current sensor 140A and voltage sensor 142A, whichare coupled to a component of the electric vehicle 12 such as system A.Using this information, the microprocessor 33 is capable of calculatingan electrical parameter associated with that particular system. Forexample, electrical resistance can be calculated using Ohms' law asR=V/I. However, other electrical parameters can be calculated such asconductance. Further still, if the electricity through the system has atime varying component, it is possible to determine dynamic parametersof the system such as dynamic resistance or conductance. Complexparameters such as impedance, reactance, etc. of the particular systemcan also be determined. Note that there may be a lag or time delaybetween the two measurements (voltage and current) due to delays in thedatabus 130 or due to other causes. Microprocessor 33 can compensate forsuch a lag by determining, or at least approximating, the duration ofthe delay. One technique which can be used is to monitor a function oractivity within the vehicle, for example, a braking function, whilemonitoring the outputs from the associated current and voltage sensors.Based upon when the current and voltage begin to change relative to oneanother, it is possible to compensate for any delays if the relationshipis known. For example, the voltage and current may be expected to risesimultaneously in some systems. If there is a lag in the voltagemeasurement, for example, the duration of that lag can be measured bymicroprocessor 33 and used to compensate subsequent measurements.Similarly, a particular sensor may have a relatively long response time,or the databus 130 may be of a sufficiently slow data rate thatsufficient band width may not be available to measure or monitor arapidly changing voltage or current. Again, compensation techniques canbe used to at least partially address such a shortcoming, for example,by providing a compensated frequency response profile for a particularsensor. This information can be used to characterize a particular sensoror measurement performed using a set of sensors. This characterizationcan compensate for such measurements in use to thereby improve theaccuracy of the measurement. The compensation characterization can bedetermined experimentally and thereby stored in the test device 14, orcan be determined empirically by monitoring operation of the vehicle 12as discussed above. This characterization information can be stored inmemory 32 of test device 14 and use to compensate the measuredparameters.

During operation, microprocessor 33 collects data from a desired system(A-N) of electric vehicle 12 using the associated current sensor 140A-Nand/or voltage sensor 140A-N as desired. The microprocessor 33 can alsouse information collected from other sensors of the electric vehicle,such as sensors A-N for use in testing as desired. If a measurement isdesired across multiple systems, it is possible to add or subtract themeasured currents and voltages to obtain such a measurement, dependingupon the configuration of the sensors. As discussed above, the data isretrieved from databus 130 using OBDII I/O circuitry 112 coupled to thedatabus 130 through OBDII connector 132. In addition to having a userinput/output 110, another optional input/output (I/O) 160 isillustrated. I/O 160 can comprise circuitry for providing data to, orreceiving data from, another device such as a remote location whichcollects data or measurements, a printer, a remote control or displayfor use by an operator, remote sensors, etc. Additionally, otheroptional sensors 162 are shown in test device 14 of FIG. 4. Sensors 162may comprise other sensors used to perform diagnostics includingphysical Kelvin connectors, current and/or voltage sensors, temperaturesensors, etc. The user I/O circuitry 110 can be used to provide aninterface for an operator during testing of electric vehicle 12. Forexample, the operator can provide information to the test device 14related to which of the systems of electric vehicle 12 to test, to aselected test to perform, to provide information regarding electricvehicle 12, etc. The I/O circuitry 110 can also be used to provideinformation to the operator such as the results of a test, intermediarytest results, information regarding past tests, information regardingthe electric vehicle 12, information regarding the history of thevehicle 12 or other information. Additionally, if a particular testrequires the electric vehicle 12 to be operated in a particular manner,the user I/O circuitry 110 can provide instructions to the operator. Forexample, the particular test being performed may require that theelectric vehicle 12 be accelerated, or that the brake be applied, thatthe electric vehicle be stopped for a period, or other actions. Theinstructions to an operator may be in the form of, for example, audibleor visual instructions which may be easily received when operating theelectric vehicle 12. Using the data collected from the sensors,microprocessor 33 can diagnose individual systems and the overalloperation of electric vehicle 12. In one example of the presentinvention, the information can be used to perform any type ofdiagnostics such as those known in the art. Various types of diagnosticsinclude measuring parameters of systems of the electric vehicle 12,monitoring the amount of energy recovered during an energy regenerativeprocess such as by recovering energy during a braking function,determining the maximum amount of energy which may be recovered, or themaximum amount of energy which the energy storage device can accept atany one time during recharging, monitoring the energy storage device asit ages to identify a loss of the capacity to store recovered energy orthe overall capacity of the storage device 20, monitoring the maximumenergy which the energy storage device 20 is capable of delivering, etc.

For example, one diagnostic technique includes monitoring a parameter ofa cell or block of cells of the battery pack 20 and observing changesover time, for example changes in impedance, conductance, resistance, orother parameters including dynamic parameters. Another examplediagnostic includes comparing parameters measured for a particular cellor block of cells of the battery pack 20 and observing any imbalancesbetween cells or blocks of cells, or other indications that a particularcell or block of cells is not operating in a manner which is similar tothe remaining cells or blocks of cells. This may be through statisticaltechniques such as observing the distribution of measurements of cellsor blocks of cells, etc. Another example diagnostic technique is simplyobserving voltage differences across cells or blocks of cells in thebattery 20.

In another example, the user I/O 110 is used to provide an outputrelated to carbon dioxide emissions of the electric vehicle 12. Forexample, the output can be an indication of the reduction in carbondioxide emissions of the electric vehicle 12 in comparison to a standardvehicle with an internal combustion engine. In a related example, theamount of energy regenerated by electric vehicle 12, for example using aregenerative braking technique, can be monitored using test device 14and an output provided using user I/O 110 which indicates the equivalentamount of carbon dioxide which would have been generated by typicalinternal combustion engine had the energy not been recovered.

In another example configuration, test device 14 can be used to monitoroperation of electric vehicle 12 and collect information related to theefficiency of the electric vehicle 12 under different operatingconditions. This information is then used by device 14 to instruct anoperator through user I/O 110 to operate the electric vehicle 12 in amanner which increases efficiency. For example, if system A shown inFIG. 4 comprises a regenerative braking system, and system B is thebattery pack 20 for the electric vehicle 12, the test device 14 can beconfigured to monitor the energy recovered by the regenerative brakingsystem and the amount of energy which the battery pack 20 is capable ofstoring. Thus, if measurements indicate that the battery pack 20 is onlycapable of accepting a maximum of 50 kW, the test device 14 can instructthe operator when braking to attempt to rapidly approach the 50 kWenergy recovering level, and maintain the 50 kW level for an extendedperiod without exceeding that level. This will ensure that the maximumamount of energy is recovered during a braking operation. Similartechniques can be used to instruct the operator during accelerationperiods, idling periods, “stop and go” traffic, etc. In a more advancedconfiguration, the device 14 is configured to control operation of thesystems in vehicle 12 in a manner which differs from the configurationprovided by the vehicle control system, for example, as implemented inthe microprocessor 150 of electric vehicle 12. For example, the testdevice 14 can provide instructions or information on databus 130 whichallows the charging system or the regeneration system of electricvehicle 12 to charge the battery pack 20 to a higher or lower level thanthat set by the internal control system of the vehicle. This may beused, for example, to extend the life of systems within the vehicle,increase the range of the vehicle, test certain systems, or for otherfunctions or purposes.

The particular test performed by the test device 14 can be a simpleevaluation and indicate and good or bad battery pack 14, or can providemore detailed information such as the total battery pack dynamicconductance or impedance, or a dynamic parameter related to anindividual cell or group of cells in the pack 20, etc. During testing,the device 14 can communicate with the operator to instruct the operatorto perform a particular operation with the vehicle, such as aggressiveacceleration or deceleration. This can be communicated through anaudible or visual technique that does not interfere with vehicleoperation such as lights, voice prompts, tones or sounds, etc. this maybe communicated to the operator using I/O components that are a part ofvehicle 12, for example, a vehicle speaker, display, etc. In oneconfiguration, the device 14 instructs the driver to operate the vehicle12 in a safe manner. If temperature data is available, for examplethrough a temperature sensor, the test measurements can be compensatedbased upon temperature. If an external PDA or cellular “smart phone”type device is used, the interface with the operator can be providedthrough such a device. For example, in one configuration, the user I/Osuch as element 110 shown in FIG. 3, comprises a remote device such as a“smart phone” capable of communicating with an operator. Communicationwith the “smart phone” can be through wireless communication techniquessuch as WiFi, Bluetooth, cellular network, etc., or can be through wiredtechniques such as a data cable or other connection.

The test device 14 can be configured to recognize when certainconditions have been met by monitoring, for example, engine speed (RPM),vehicle miles per hour, vehicle acceleration and deceleration, etc. Thiscan be by using instruments onboard the vehicle 12 such as GPSinformation, the output from a speedometer, etc. Once a complete dataset has been obtained as desired for a particular test, the test device14 can provide an output accordingly. The test can be modified basedupon driving conditions and the duration of the test can be extended asneeded. Instructions can be provided to the operator and, in someconfigurations, the operation of the vehicle 12 can be controlled by thetest device 14. For example, gearing or braking of vehicle 12 can becontrolled, requesting the vehicle 12 enter “EV” mode, operating certainaccessories on the vehicle, monitoring acceleration or braking,monitoring torque provided by vehicle motors, engine parameters such asfuel mix, etc can be monitored or controlled, or other elementscontrolled or monitored as desired. The operator can be informed thatthe vehicle 12 is being operated correctly or incorrectly using anaudible or visual output. Any “trouble codes” available on the databusof vehicle 12 can also be incorporated into the testing. One type oftest involves the vehicle 12 being “blocked”, in other words placed ontoa test stand in which the vehicle 12 is operated on rollers. The testdevice 14 can be configured to operate in such a mode for use inmonitoring acceleration and deceleration tests, etc. If the test device14 is temporarily coupled to the vehicle 12, it can be configured to beleft in the vehicle 12 for an extended period while an operator drivesthe vehicle 12 under normal operating conditions. This allows thevehicle 12 to be monitored during “real life” drive cycles as data iscollected. In one configuration, the test device 15 monitorsinstantaneous fuel usage and combines this fuel usage with a batterytest. This information can be useful in identifying bad battery packs orbattery within the pack 20 and used to monitor the efficiency of thecharging cycle. A poor charging cycle indicates a bad battery and willresult in increased fuel usage. The test device 14 can record the fuelusage, the number of starts, or other information and store suchinformation in a flash memory for subsequent recovery.

Although the present invention has been described with reference topreferred embodiments, workers skilled in the art will recognize thatchanges may be made in form and detail without departing from the spiritand scope of the invention. For example, although storage batteries or a“battery pack” described, as used herein the term electric energystorage device includes a battery or collection of batteries, capacitorsincluding supercapacitors and ultracapacitors, and other electricalenergy storage devices. As used herein, electric vehicle includes anytype of vehicle which uses an electric motor to propel, or assist inpropelling, the vehicle. One example electric vehicle is a vehicle withan electric motor and an electric storage device such as a battery packor the like. Another example electric vehicle is an electric vehiclewith regenerative techniques in which energy is recovered, for example,from the braking process. Another example electric vehicle is a hybridvehicle which also includes an internal combustion engine for use insupplementing electric power, and/or charging the electrical energystorage device. Such a hybrid vehicle may optionally includeregenerative systems for energy recovery. As used herein, “operating” anelectric vehicle includes using the vehicle, or systems of the vehicle,and is not limited to driving the vehicle. In one configuration the testdevice is separate from the vehicle and may be selectively coupled tothe vehicle or added after manufacture of the vehicle. The “virtual”Kelvin configuration can be used to calculate a parameter of a system ofthe vehicle using two or more inputs from sensors which are transmittedover a databus of the vehicle.

1. A method of testing an electrical system of an electric vehicle,comprising: operating the electric vehicle; coupling to a databus of theelectric vehicle; monitoring data on the databus and retrievinginformation related to current flowing into a system of the electricvehicle during the step of operating; monitoring data on the databus andretrieving information related to a voltage of the system during thestep of operating; and diagnosing the electric vehicle based upon themonitored current and the monitored voltage.
 2. The method of claim 1including instructing an operator regarding operation of the electricvehicle.
 3. The method of claim 1 wherein diagnosing includes comparingmonitored current and monitored voltage with nominal values.
 4. Themethod of claim 1 including wirelessly communicating information.
 5. Themethod of claim 1 wherein the databus comprises an OBDII databus.
 6. Themethod of claim 1 wherein the system comprises a battery pack of thevehicle.
 7. The method of claim 6 including monitoring a second systemof the vehicle.
 8. The method of claim 7 wherein the second systemcomprises a regenerative braking system of the vehicle.
 9. The method ofclaim 8 wherein diagnosing comprises monitoring energy output from theregenerative braking system and monitoring energy input into the batterypack.
 10. The method of claim 9 wherein the diagnosing further comprisesdetermining efficiency of a transfer of energy recovered from theregenerative braking system and stored in the battery pack.
 11. Themethod of claim 1 wherein the system comprises a block of cells of abattery pack of the electric vehicle.
 12. The method of claim 11including monitoring a second block of at least one or more cells of thebattery pack.
 13. The method of claim 12 wherein the diagnosingcomprises comparing a parameter of the first block of cells with aparameter of the second block of cells.
 14. The method of claim 1wherein the diagnosing comprises measuring a parameter of the system.15. The method of claim 14 wherein the parameter comprises a dynamicparameter.
 16. The method of claim 1 including providing an output to anoperator of the electric vehicle.
 17. The method of claim 16 wherein theoutput comprises instructions related to operation of the vehicle foruse in performing the step of diagnosing.
 18. The method of claim 1wherein the electric vehicle comprises a hybrid vehicle.
 19. The methodof claim 18 wherein the system comprises an electric generator coupledto an internal combustion engine of the electric vehicle.
 20. The methodof claim 19 including monitoring a second system of the electricvehicle, wherein the second system comprises a battery pack and the stepof diagnosing comprises determining efficiency of storage of energy fromthe generator by the battery pack.
 21. The method of claim 1 wherein thediagnosing includes compensating for a difference between retrievinginformation related to current flowing into the system and retrievinginformation related to the voltage of the system.
 22. The method ofclaim 1 including placing information onto the databus which affectsoperation of the electric vehicle.
 23. The method of claim 1 includingplacing information onto the databus which affects operation of a systemof the electric vehicle.
 24. The method of claim 1 including providingan output to an operator of the vehicle to instruct the operator tooperate the vehicle in a manner to increase energy efficiency of thevehicle.
 25. An apparatus for testing an electric vehicle, comprising: adatabus connector configured to connect to a databus of the electricvehicle; a microprocessor configured to: retrieve voltage informationfrom the databus of the electric vehicle provided by a voltage sensorcoupled to a system of the electric vehicle; retrieve currentinformation from the databus of the electric vehicle provided by acurrent sensor coupled to the system of the electric vehicle; anddiagnose the operation of the vehicle based upon the retrieved currentinformation and the retrieved voltage information.
 26. The apparatus ofclaim 25 wherein the microprocessor compares monitored current andmonitored voltage or a function of monitored voltage and monitoredcurrent, with nominal values.
 27. The apparatus of claim 25 wherein thedatabus comprises an OBDII databus.
 28. The apparatus of claim 25wherein the system comprises a battery pack of the vehicle.
 29. Theapparatus of claim 28 wherein the microprocessor monitors a secondsystem of the vehicle.
 30. The apparatus of claim 29 wherein the secondsystem comprises a regenerative braking system.
 31. The apparatus ofclaim 30 wherein the microprocessor monitors energy output from theregenerative braking system and monitors energy input into the batterypack.
 32. The apparatus of claim 31 wherein the microprocessor furtherdetermines efficiency of the transfer of energy recovered from theregenerative braking system and stored in the battery pack.
 33. Theapparatus of claim 25 wherein the system comprises a block of one ormore cells of a battery pack of the electric vehicle.
 34. The apparatusof claim 33 wherein the microprocessor monitors a second block of one ormore cells of the battery pack.
 35. The apparatus of claim 34 whereinthe microprocessor compares a parameter of the first block of cells witha parameter of the second block of cells.
 36. The apparatus of claim 25wherein the microprocessor measures a parameter of the system.
 37. Theapparatus of claim 36 wherein the parameter comprises a dynamicparameter.
 38. The apparatus of claim 25 including an output provided toan operator of the electric vehicle.
 39. The apparatus of claim 38wherein the output comprises instructions related to operation of thevehicle for use in performing the step of diagnosing.
 40. The apparatusof claim 25 wherein the electric vehicle comprises a hybrid vehicle. 41.The apparatus of claim 25 wherein the system comprises an electricgenerator coupled to an internal combustion engine of the electricvehicle.
 42. The apparatus of claim 41 wherein the microprocessormonitors a second system of the electric vehicle, wherein the secondsystem comprises a battery pack and the microprocessor determinesefficiency of storage of energy from the generator by the battery pack.43. The apparatus of claim 25 wherein the microprocessor compensates fora difference between retrieving information related to current flowinginto the system and retrieving information related to a voltage of thesystem.
 44. The apparatus of claim 25 wherein the microprocessor isconfigured to place information onto the databus which affects operationof the electric vehicle.